First version

.github/dependabot.yml

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+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "daily"

.github/workflows/ci.yml

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+name: CI
+
+on:
+  pull_request:
+  push:
+    branches: main
+
+jobs:
+  generate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - id: generate
+        uses: freckle/stack-action/generate-matrix@v5
+    outputs:
+      stack-yamls: ${{ steps.generate.outputs.stack-yamls }}
+
+  test:
+    runs-on: ubuntu-latest
+    needs: generate
+
+    strategy:
+      matrix:
+        stack-yaml: ${{ fromJSON(needs.generate.outputs.stack-yamls) }}
+      fail-fast: false
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: freckle/stack-action@v4
+        with:
+          stack-yaml: ${{ matrix.stack-yaml }}
+
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: haskell-actions/hlint-setup@v2
+      - uses: haskell-actions/hlint-run@v2
+        with:
+          fail-on: warning

.github/workflows/mergeabot.yml

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+name: Mergeabot
+
+on:
+  pull_request:
+  schedule:
+    - cron: "0 0 * * *"
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  mergeabot:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: freckle/mergeabot-action@v1
+        with:
+          quarantine-days: -1

.github/workflows/restyled.yml

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+name: Restyled
+
+on:
+  pull_request:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  restyled:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: restyled-io/actions/setup@v4
+      - uses: restyled-io/actions/run@v4
+        with:
+          suggestions: true

.gitignore

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+.stack-work

.restyled.yaml

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+restylers:
+  - hlint
+  - fourmolu
+  - "!stylish-haskell"
+  - "*"

LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2024 Renaissance Learning Inc
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# WAI OpenAPI Middleware
+
+Validates request and response bodies against your service's OpenAPI spec.
+
+This is useful in a non-Servant web application, where OpenAPI specs cannot be
+generated from the API implementation itself, and so must be maintained
+manually.
+
+## Usage
+
+```hs
+import Network.Wai (Middleware)
+import Network.Wai.Middleware.OpenApi qualified as OpenApi
+
+middleware :: Middleware
+middleware =
+  thisMiddleware
+    . thatMiddleware
+    . OpenApi.validate openApi
+    . theOtherMiddleware
+
+-- Defined in your /docs or /openapi.json Handler
+openApi :: OpenApi
+openApi = undefined
+```
+
+Default behavior:
+
+- If a request body is invalid, a 400 is returned
+- If a response body is invalid, a 500 is returned
+- In both cases, the validation errors are included in the response body
+
+This is useful if you,
+
+1. Are confident your server is currently complying with spec
+2. Trust your spec enough to reject all invalid-according-to-it requests
+3. Trust your observability to catch the 5xx increase any future
+   response-validity bug would cause
+
+If all or some of these are not true, see the next section.
+
+## Configuring
+
+The `validate` function is equivalent to,
+
+```hs
+validateRequests defaultOnRequestErrors
+  . validateResponses defaultOnResponseErrors
+```
+
+Where those "on" functions take the appropriate error type and return a
+`Middleware`. The reason it returns a middleware is so that it can decide if it
+should take over the response or let it run normally:
+
+```hs
+defaultOnRequestErrors :: RequestErrors -> Middleware
+defaultOnRequestErrors = \case
+  RequestSchemaNotFound {} -> id -- respond normally
+  RequestIsNotJson {} -> id
+  RequestInvalid _ errs -> \_ _ respond ->
+    respond $ clientErrorResponse errs -- respond with an error
+```
+
+Implementing and using a function like this would be how you:
+
+1. Decide to error on missing schema, etc
+2. Change the shape of of the JSON errors
+3. Emit non-JSON errors
+
+## Evaluation
+
+When first implementing this, you probably want to log invalid cases but still
+respond normally. To support this use-case, the library ships replacements for
+`defaultOn*` that are named `evaluateOn*`. These functions take an action to
+apply to the errors (presumably to log them) and then responds normally.
+
+```hs
+validateRequests (evaluateOnRequestErrors logIt)
+  . validateResponses (evaluateOnResponseErrors logIt)
+
+logIt :: Show e => e -> IO ()
+logIt = undefined
+```
+
+The action is necessarily `IO` because we're in a WAI middleware context.
+
+## Performance & Sampling
+
+This middleware may add a performance tax depending on the size of your typical
+requests, responses, and OpenAPI spec itself. If you are concerned, we recommend
+enabling this middleware on a sampling of requests.
+
+For example,
+
+```hs
+openApiMiddleware :: OpenApi.Settings -> Middleware
+openApiMiddleware settings =
+  -- Only validate 20% of requests
+  sampledMiddleware 20 $ OpenApi.validate spec
+
+sampledMiddleware :: Int -> Middleware -> Middleware
+sampledMiddleware percent m app request respond = do
+  roll <- randomRIO (0, 100)
+  if percent <= roll
+    then m app request respond
+    else app request respond
+```
+
+> [!NOTE]
+> We will likely upstream `sampledMiddleware` to `wai-extra` at some point.
+
+---
+
+[CHANGELOG](./CHANGELOG.md) | [LICENSE](./LICENSE)

fourmolu.yaml

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+indentation: 2
+column-limit: 80 # ignored until v12 / ghc-9.6
+function-arrows: leading
+comma-style: leading # default
+import-export-style: leading
+indent-wheres: false # default
+record-brace-space: true
+newlines-between-decls: 1 # default
+haddock-style: single-line
+let-style: mixed
+in-style: left-align
+single-constraint-parens: never # ignored until v12 / ghc-9.6
+unicode: never # default
+respectful: true # default
+fixities:
+  - "infix 4 `stringEqual`"
+  - "infixl 1 &"

package.yaml

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+name: wai-middleware-openapi
+version: 0.0.0.0
+maintainer: Freckle Education
+category: Web
+synopsis: TODO
+description: TODO
+
+extra-doc-files:
+  - README.md
+  - CHANGELOG.md
+
+ghc-options:
+  - -Weverything
+  - -Wno-all-missed-specialisations
+  - -Wno-missed-specialisations
+  - -Wno-missing-exported-signatures # re-enables missing-signatures
+  - -Wno-missing-import-lists
+  - -Wno-missing-local-signatures
+  - -Wno-monomorphism-restriction
+  - -Wno-safe
+  - -Wno-unsafe
+
+when:
+  - condition: "impl(ghc >= 9.2)"
+    ghc-options:
+      - -Wno-missing-kind-signatures
+  - condition: "impl(ghc >= 8.10)"
+    ghc-options:
+      - -Wno-missing-safe-haskell-mode
+      - -Wno-prepositive-qualified-module
+
+dependencies:
+  - base < 5
+
+language: GHC2021
+
+default-extensions:
+  - DataKinds
+  - DeriveAnyClass
+  - DerivingStrategies
+  - DerivingVia
+  - DuplicateRecordFields
+  - GADTs
+  - LambdaCase
+  - NoFieldSelectors
+  - NoImplicitPrelude
+  - NoMonomorphismRestriction
+  - NoPostfixOperators
+  - OverloadedRecordDot
+  - OverloadedStrings
+  - QuasiQuotes
+  - TypeFamilies
+
+library:
+  source-dirs: src
+  dependencies:
+    - aeson
+    - bytestring
+    - filepath
+    - http-media
+    - http-types
+    - insert-ordered-containers
+    - lens
+    - mtl
+    - openapi3
+    - text
+    - wai
+
+tests:
+  spec:
+    main: Spec.hs
+    source-dirs: tests
+    ghc-options: -threaded -rtsopts "-with-rtsopts=-N"
+    dependencies:
+      - aeson
+      - hspec
+      - http-types
+      - insert-ordered-containers
+      - lens
+      - openapi3
+      - text
+      - wai
+      - wai-extra
+      - wai-middleware-openapi
+
+  # readme:
+  #   main: README.lhs
+  #   ghc-options: -pgmL markdown-unlit
+  #   dependencies:
+  #     - Blammo
+  #     - amazonka-core
+  #     - amazonka-mtl
+  #     - amazonka-s3
+  #     - conduit
+  #     - lens
+  #     - markdown-unlit
+  #     - mtl